Java SDK 示例

首先向工程项目pom 文件中添加依赖：

<dependencies>
    <!-- Hadoop 依赖 -->
    <dependency>
        <groupId>org.apache.hadoop</groupId>
        <artifactId>hadoop-hdfs</artifactId>
        <version>${hadoop.version}</version>
    </dependency>

    <dependency>
        <groupId>org.apache.hadoop</groupId>
        <artifactId>hadoop-common</artifactId>
        <version>${hadoop.version}</version>
    </dependency>

    <dependency>
        <groupId>org.apache.hadoop</groupId>
        <artifactId>hadoop-mapreduce-client-core</artifactId>
        <version>${hadoop.version}</version>
    </dependency>

    <!-- Hive依赖 -->
    <dependency>
        <groupId>org.apache.hive</groupId>
        <artifactId>hive-standalone-metastore</artifactId>
        <version>${hive.version}</version>
    </dependency>

    <dependency>
        <groupId>org.apache.hive</groupId>
        <artifactId>hive-common</artifactId>
        <version>${hive.version}</version>
    </dependency>

    <dependency>
        <groupId>org.apache.hive</groupId>
        <artifactId>hive-exec</artifactId>
        <version>${hive.version}</version>
    </dependency>

    <dependency>
        <groupId>org.apache.hive</groupId>
        <artifactId>hive-jdbc</artifactId>
        <version>${hive.version}</version>
    </dependency>
</dependencies>

kerberos 验证代码如下：

private static void handleKerberos(HiveConf hiveConf, String keytab, String keytabPrincipal) throws Exception {
    LOG.info("CONFIG: hive.server2.authentication -> " + hiveConf.getVar(HiveConf.ConfVars.HIVE_SERVER2_AUTHENTICATION));

    // 如果没有启用Kerberos认证则给出警告
    if (!hiveConf.getBoolVar(HiveConf.ConfVars.METASTORE_USE_THRIFT_SASL)) {
        LOG.warn("kerberos is not used");
        return;
    }
    // 认证Kerberos
    System.setProperty("java.security.krb5.conf", "/etc/krb5.conf");
    System.setProperty("javax.security.auth.useSubjectCredsOnly", "false");
    UserGroupInformation.setConfiguration(hiveConf);
    LOG.info("UserGroupInformation.loginUserFromKeytab keytabPrincipal ->" + keytabPrincipal + " keytab -> " + keytab);
    UserGroupInformation.loginUserFromKeytab(keytabPrincipal, keytab);
}

参数说明：1、keytab：给定用户的 keytab 文件路径；2、keytabPrincipal：对应的 principal。

获取 Hive Metastore 客户端：

/**
 * 获取 Hive 对象
 *
 * @param hiveConf Hive 配置信息
 * @return Hive 对象
 * @throws HiveException
 */
public static IMetaStoreClient getHiveClient(HiveConf hiveConf) throws Exception {
    try {
        IMetaStoreClient hmsClient = RetryingMetaStoreClient.getProxy(hiveConf, false);
        return hmsClient;
    } catch (Exception e) {
        LOG.error("setHiveMetaStoreConf error", e);
        throw e;
    }
}

获取所有的数据库名称：

/**
 * 获取Hive数据库中所有的库名称
 *
 * @param hmsClient Metastore客户端
 * @return 库名称列表
 * @throws TException
 */
public static List<String> getDatabases(IMetaStoreClient hmsClient) throws TException {
    return hmsClient.getAllDatabases();
}

获取指定数据库中所有的表名称：

/**
 * 获取指定数据库中所有的表名称
 *
 * @param hmsClient Metastore客户端
 * @param dbName 数据库名称
 * @return 表名称列表
 * @throws TException
 */
public static List<String> getTables(IMetaStoreClient hmsClient, String dbName) throws TException {
    return hmsClient.getAllTables(dbName);
}

与HiveServer2 交互并进行查询的流程如下：

一个简单的示例代码如下：

public class JDBCExample {

    // Hive JDBC 驱动的类名
    private static final String HIVE_DRIVER = "org.apache.hive.jdbc.HiveDriver";

    // 使用 SLF4J 日志记录器
    private static final Logger LOG = LoggerFactory.getLogger(JDBCExample.class);

    public static void main(String[] args) throws ClassNotFoundException, SQLException {
        // 获取 Hive 配置信息
        // 默认会搜寻 $HIVE_HOME/conf/hive-site.xml 以及其他资源文件
        HiveConf hiveConf = HiveUtils.getHiveConf();

        // 处理 Kerberos 认证
        try {
            HiveUtils.handleKerberos(hiveConf);
        } catch (Exception e) {
            // 如果 Kerberos 认证失败，记录错误日志并退出
            LOG.error("Kerberos authentication failed, due to {} ", e.getMessage(), e);
            return;
        }

        // 加载 Hive JDBC 驱动类
        Class.forName(HIVE_DRIVER);
        Connection connection = null;

        // JDBC 连接 URL，用户名和密码
        String url = "jdbc:hive2://<hiveserver2_url>"; // 替换为实际的 HiveServer2 URL
        String usr = "hive"; // 用户名
        String password = ""; // 密码

        // 尝试建立与 HiveServer2 的连接
        try {
            connection = DriverManager.getConnection(url, usr, password);
        } catch (SQLException e) {
            // 如果连接失败，记录错误日志并退出
            LOG.error("Fail to connect HiveServer2: {}, due to {}", url, e.getMessage(), e);
            return;
        }

        // 创建用于执行 SQL 查询的 Statement 对象
        Statement stmt = connection.createStatement();
        ResultSet resultSet = null;

        // 执行 SQL 查询并捕获结果
        try {
            resultSet = stmt.executeQuery("SELECT * FROM example limit 10");
        } catch (Exception e) {
            // 如果执行查询失败，记录错误日志
            LOG.error("Fail to execute, due to {}", e.getMessage(), e);
        }

        // 如果结果集为空，记录日志并退出
        if (resultSet == null) {
            LOG.info("Unable to retrieve any data");
            return;
        }

        // 获取结果集的列数
        int columns = resultSet.getMetaData().getColumnCount();
        int rowIndex = 1;

        // 遍历结果集的每一行
        while (resultSet.next()) {
            StringBuilder sb = new StringBuilder();

            // 遍历每一列并将值添加到 StringBuilder
            for (int i = 1; i <= columns; i++) {
                String row = resultSet.getString(i);
                sb.append(row);

                // 在列之间添加制表符作为分隔符
                if (i != columns) {
                    sb.append(' ');
                }
            }

            // 记录结果集中的当前行
            LOG.info("{} %{}", rowIndex++, sb);
        }
    }
}